Actuator base nubbin alignment

Abstract

In accordance with the teachings of the present invention, a mold comprises a nubbin positioned within the mold, and an actuator positioned within the mold to align the nubbin. The actuator may be implemented with a piezoelectric material, a magnetorestrictive material, an electrorestrictive material, etc. In one embodiment, the actuator is formed into a cylinder and placed around a nubbin in a mold. When the actuator receives a stimulus, the actuator constricts decreasing the size of the inner diameter. Decreasing the size of the inner diameter causes the actuator to constrict and align the nubbin along a centerline.

Description

FIELD OF THE INVENTION[0001]The invention relates to the production of precision molded parts. Specifically, the invention relates to a method for improving the alignment of sections of a mold.BACKGROUND OF THE INVENTION[0002]Precise alignment of adjacent sections of a mold is critical to the production of a precision-molded part such as a lens. The alignment of adjacent sections of a mold is most challenging when the adjacent sections are positioned across the parting line of the mold. Once the mold is aligned a molded part may be produced with the accuracy and tolerances required by the designer. For example, it is envisioned that some applications will require an alignment precision of less than ½ a micron.[0003]During the molding operation, the accuracy of the alignment between adjacent sections of the mold determines the accuracy of the optical surfaces of the molded lens. The performance of the molded lens is often limited by the accuracy of the alignment of the optical surfac...

AI Technical Summary

Benefits of technology

[0022]The present invention precisely aligns two sections of a mold and precisely centers a nubbin within a mold with minimal complexity.

Problems solved by technology

The alignment of adjacent sections of a mold is most challenging when the adjacent sections are positioned across the parting line of the mold.

The performance of the molded lens is often limited by the accuracy of the alignment of the optical surfaces of the lens relative to each other.

Misalignment of the axis of one surface of a lens relative to the axis of the other surface of the lens is the major contributor to lens irregularity problems such as coma and RMS.

Ultimately, the lens problems impact the imaging quality of the lens.

Misalignment of the optical surfaces in the mold cavity results in the misalignment of the axes of the surfaces of the molded lens.

As a result, when the nubbins are not properly aligned, the axis of each side of the lens is misaligned.

Multiplying this by the number of guide pins and combining this for both mold halves, results in a 10 to 20 micron misalignment problem resulting from the guide pins.

A number of studies have shown that the nubbin clearance is a major contributor to misalignment in a molded plastic lens.

Nubbin alignment in plastic lens molding is difficult to control due to the need for clearance around a first nubbin (i.e., found in the first half of the mold) that enables the first nubbin to move during ejection of the molded lens after molding.

However, the design in Hosoe is complex.

In addition, since the control of the flowing gas is complex, the piping disclosed in Hosoe is elaborate and difficult to include in a mold.

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